/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.nutch.crawl;
import java.io.IOException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.Mapper;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reporter;
import org.apache.nutch.net.URLFilters;
import org.apache.nutch.net.URLNormalizers;
/**
* This class provides a way to separate the URL normalization
* and filtering steps from the rest of CrawlDb manipulation code.
*
* @author Andrzej Bialecki
*/
public class CrawlDbFilter implements Mapper {
public static final String URL_FILTERING = "crawldb.url.filters";
public static final String URL_NORMALIZING = "crawldb.url.normalizers";
public static final String URL_NORMALIZING_SCOPE = "crawldb.url.normalizers.scope";
private boolean urlFiltering;
private boolean urlNormalizers;
private URLFilters filters;
private URLNormalizers normalizers;
private JobConf jobConf;
private String scope;
public static final Log LOG = LogFactory.getLog(CrawlDbFilter.class);
public void configure(JobConf job) {
this.jobConf = job;
urlFiltering = job.getBoolean(URL_FILTERING, false);
urlNormalizers = job.getBoolean(URL_NORMALIZING, false);
if (urlFiltering) {
filters = new URLFilters(job);
}
if (urlNormalizers) {
scope = job.get(URL_NORMALIZING_SCOPE, URLNormalizers.SCOPE_CRAWLDB);
normalizers = new URLNormalizers(job, scope);
}
}
public void close() {}
private Text newKey = new Text();
public void map(WritableComparable key, Writable value, OutputCollector output, Reporter reporter) throws IOException {
String url = key.toString();
if (urlNormalizers) {
try {
url = normalizers.normalize(url, scope); // normalize the url
} catch (Exception e) {
LOG.warn("Normalize skipping " + url + ":" + e);
url = null;
}
}
if (url != null && urlFiltering) {
try {
url = filters.filter(url); // filter the url
} catch (Exception e) {
LOG.warn("Filtering skipping " + url + ":" + e);
url = null;
}
}
if (url != null) { // if it passes
newKey.set(url); // collect it
output.collect(newKey, value);
}
}
}